I cannot show you my success as it is not on our site's main theme

I had to edit the stylesheet
theme/styles/style.css

I altered nothing else just added these lines near the bottom

body{
background-color:#003942;
background-image:url(/sky.jpg);
background-position:top;
background-repeat:repeat-x;
color:#9ED3E0;
margin:0px;
padding:0px;
}


hope this helps ya (the image i put in my root folder and just put the / before it
but you could have it in the theme folder e.g. themes/smartDark/images/sky.jpg
knowing where to put / can cause problems, just keep playing with it, it should work.

Also...if you don't want the background image to move with the page

BODY {
background:#000000 url("/sky.jpg") fixed top;
background-repeat:repeat-x;
padding-top:0px;
padding-left:0px;
padding-right:0px;
margin:0px
}

again, not sure about the / or the "", I'm just copying this stuff..
the repeat command is for images that are less than the entire width of the page, otherwise you would have the line

background:#000000 url("/sky.jpg") no-repeat fixed top;

. :wink: